Best of 2016 in Pictures: The most captivating wildlife photographs of the year

Bjorn, aged 5, smiles as he poses with a Owl butterfly during an event to launch the Sensational Butterflies exhibition at the Natural History Museum in London, Britain.Reuters

A rat's head rests as it is constricted in an opening in the bottom of a garbage can in Brooklyn, New York, October 18, 2016Reuters

A polar bear is seen at an aquarium in Guangzhou, Guangdong province, China, July 27, 2016.Reuters

A polar bear is seen at an aquarium in Guangzhou, Guangdong province, China, July 27, 2016.Reuters

A golden pheasant is seen at Hangzhou Safari Park in Hangzhou, Zhejiang Province, China.Reuters

Riders and their horses of the Spanish Riding School of Vienna perform a dress rehearsal for the media at the SSE Arena in London, Britain November 10, 2016Reuters

A 23-day-old hamadryas baboon plays with a stuffed toy at Sri Chamarajendra Zoological Gardens after the baboon, according to a zoo doctor, was abandoned by its mother after its birth on April 4, in the southern city of Mysuru, India, April 28, 2016.Reuters

A sloth holds on to the post of a traffic barrier on a highway, in this handout photo provided by Ecuador's Transit Commission, in Quevedo, Ecuador.Reuters

A giant panda cub falls from the stage while 23 giant pandas born in 2016 are seen on a display at the Chengdu Research Base of Giant Panda Breeding in Chengdu, Sichuan province, China September 29, 2016.Reuters

A cat with a "stegosaurus spine" design cut into its fur is seen next to a dog at a pet shop, in Tainan, Taiwan.Reuters